A display interface, such as a graphical user interface (GUI), represents a well known presentation medium for displaying computer data to a user. A GUI typically comprises a variety of display items, each having an appearance defined by one or more controllable parameters. Because users often have different views about the way a GUI should look, computer software designers have created controls that allow users to change these parameters and to customize the appearance of the GUI.
A dialog is a typical control device for enabling a user to view and select desired parameters to control the appearance of a display item. From a user's perspective, a dialog often presents a wide variety of possible control options, each requiring the user to readily understand its operation based on the text or image associated with a particular control. A "busy" dialog can offer a rather intimidating display for the typical user because it fails to support intuitive control operations. In other words, a dialog typically provides the typical user with multiple discrete options for varying the presentation of a display item, which can often lead to a user's confusion regarding the associated control operations.
Prior mechanisms for controlling parameters of a display interface also include radio buttons and pull-down menus. For radio buttons, the user typically moves the cursor onto a button associated with the desired parameter and then selects the button to change its state. Pull-down menus generally require the user to move the cursor to a desired menu, select the menu, find and select the desired parameter in the menu, and then release, thereby controlling the state of the desired parameter. To set multiple parameters, each of these prior control devices must be operated numerous times. This can be time consuming and tedious for the typical user.
A collection or set of radio buttons also presents a cluttered user interface and occupies a substantial amount of screen space. Tags or labels are typically placed proximate to radio buttons denoting the function of each button. Many programs are adapted for use in non-English speaking environments. Because each tag requires translation for a non-English speaking audience, the text and supporting source code for each tag would need to be modified. This presents time management issues for a programmer. Moreover, a translation of the tag text may lead to a translated tag occupying additional screen space, thereby contributing to an already cluttered user interface. Similar translation issues are presented by the text used in drop-down menus.
In view of the foregoing, there is a need in the art for a system for changing parameters of a controllable display item by use of a single control that provides an intuitive mechanism for varying the presentation of the display item. In addition, there is a need for a control mechanism that occupies a limited amount of screen space for a user interface, while providing control features that are easy for a typical user to operate to control parameters of a display item. There is a further need for a control mechanism for controlling the parameters of a display item in a manner that exhibits a universal view of operation.